The present invention relates to a process for forming agglomerates or compacts from a feed material comprising solid particles in contact with a liquid (e.g., carboniferous particulates such as bituminous, subbituminous and lignite coal and/or coal fines in contact with water) which does not require the use of a binder. The process of the present invention can be used to form cylindrically-shaped compacts from carboniferous particles (i.e., "coal logs") so that the material can be handled and transported more easily by conventional means (e.g., truck, barge, conveyor etc.) or by a hydraulic coal log pipeline, such as that described and shown in U.S. Pat. No. 4,946,317 (Liu et al.).
Coal is widely used as a fuel source for generating heat. Coal is often transported over long distances from the mining area to the end user. In order that coal remain an attractive fuel source, it is imperative that means be devised to transport coal efficiently and economically.
Coal fines are extremely small coal particles typically having a diameter of about 1 mm or less. Coal fines are produced in significant quantities by the washing of mined coal and possess a potentially significant heating value. However, their large water content often makes them difficult to handle and use as a fuel source. Currently, because coal fines cannot be dewatered and processed into a form which may be easily transported economically, they are usually collected in tailing ponds as a waste product of coal mining or coal preparation operations rather than being recovered. Coal fines represent a significant environmental problem which would be reduced if a process were available which could economically convert coal fines into a usable fuel source.
It has been suggested that mined coal particles, coal fines and other carboniferous particles could be processed into a more easily transportable and usable form by fabricating agglomerates or compacts from the material. It is generally known that loose particles of coal can be formed into agglomerates or compacts (e.g., briquettes as well as other shapes) by compacting or extruding a mixture of coal particles and a significant amount of a binder additive (e.g., pitch). However, the use of binders in forming coal compacts is generally undesirable because the binders add to the expense and complexity of the process, cause increased smoking when the compact is subsequently burned and render the compact generally unpleasant to handle. As a result, binderless coal compaction or extrusion processes have been developed. However, prior art binderless processes are energy intensive, expensive and often do not produce a compact having the mechanical strength characteristics necessary to withstand the rigors of handling and transport without breaking. Furthermore, prior art compaction and extrusion processes are not capable of economically producing a suitable compact from coal fines.